Fractional initial phase, First is the fractional initial phase , which occurs at the receiver at the first instant of the lock-on. The receiver starts tracking the incoming phase from the satellite. It cannot yet know how to achieve a perfect synchronization. Lacking this knowledge the receiver grabs onto the satellite’s signal at some fractional part of a phase. It is interesting to note that this fractional part does not change for the duration of the observation and so is called the fractional initial phase. It is symbolized in the equation above by α